This application claims priority based on Japanese Patent Applications No. 11-258048 filed on Sep. 10, 1999 and No. 2000-267054 filed on Sep. 4, 2000, the entire contents of which are incorporated by reference for all purposes.
The present invention relates to an entertainment system, an information processing unit used therefor, and a portable storage device detachably mounted to the information processing unit.
In an entertainment system including an information processing unit and a memory card detachably mounted to the unit, the memory card serves as an external storage device for the information processing unit. The memory card includes a flash read only memory (ROM), a control circuit, a clock generating circuit, and a connection terminal. When the memory card is connected to the information processing unit, the memory card communicates with the information processing unit through the connection terminal. The control circuit executes communication control and reading and writing control from/to the flash ROM. The control circuit is formed of a gate array. Power for operating the memory card is supplied from the information processing unit through the connection terminal.
The memory card stores information in the flash ROM on a file basis. In a particular region of the memory card, there is provided a file management system for managing the files. The file management system manages the use condition of the flash ROM such that addresses in the flash ROM and files stored in the flash ROM correspond. The file management system is stored in a particular region on the flash ROM.
The file management system is first loaded onto the memory within the main body of the information processing unit from the flash ROM so that the information processing unit can access the memory card. Then, referring to information in the loaded file management system, an address of a file to be accessed or of an empty region is obtained. When the information processing unit access the flash ROM, the information processing unit directly specifies the address and reading and writing is performed from/to the address. When the information processing unit updates or deletes a file on the flash ROM, the state of the flash ROM changes. At this time, the information processing unit updates the file management system loaded in the memory within the main body of the information processing unit. Then, the contents of the updated file management system are written back to the memory card.
Note, however, that it takes a longer period for the information processing unit to read/write from/to the flash ROM than accessing the memory within the main body of the information processing unit. Therefore, if reading and writing must often be executed from/to the flash ROM, the processing speed of the entire entertainment system itself is lowered. As a result, once the file management system has been loaded into the information processing unit, the file management system is not reloaded unless the state of the flash ROM changes. This prevents the processing speed from unnecessarily being lowered.
Here, there is a problem associated with insertion/extraction of the memory card. The entertainment system allows the memory card to be inserted/extracted as desired, while the power supply for the information processing unit is on. This is for the convenience of the user. The file management system however is peculiar to each memory card. For example, assume that a file management system is loaded into the memory within the main body of an information processing unit from a memory card, and then the memory card is replaced with another card. The file management system loaded is not a file management system for the inserted memory card. At this time, if the flash ROM of the memory card is accessed based on information in the loaded file management system, the contents of data may be contradictory, or the contents of the flash ROM could be destroyed.
Therefore, the information processing unit must know insertion/extraction of the memory card. One method therefor is to provide a switch at a connector portion of the information processing unit. More specifically, the switch is adapted to output an on/off signal when the memory card is inserted/extracted. If these signals are transmitted to a central processing unit (CPU) by an interrupt, the information processing unit can be informed of the insertion/extraction of the memory card in real time. In this case, however, such a switch must be separately provided. This increases the number of parts, which pushes up the cost.
The CPU may monitor the insertion/extraction of the memory card for every fixed time period. However, the insertion/extraction of the memory card does not occur very often in normal use. Therefore, the time spent by the CPU for monitoring could be mostly wasted. As a result, the processing efficiency of the entire entertainment system is lowered.
It is an object of the present invention to provide: (i) an information processing unit which can be kept informed of the insertion/extraction of a portable storage device without requiring any special parts or special mechanisms, and without increasing the processing load of the information processing unit; and (ii) a portable storage device detachable to the information processing unit.
In order to achieve the above-described object, there is provided an entertainment system according to a first aspect of the present invention which includes a portable storage device, and an information processing unit to which the portable storage device is detachably connectable. The portable storage device includes: a first storage unit whose storage contents are held when the portable storage device is disconnected from the information processing unit; and second storage unit whose storage contents are not held when the portable storage device is disconnected from the information processing unit. The information processing unit includes: means for writing to the second storage unit information indicating that the information processing unit and the portable storage device are connected; and means for referring to the second storage unit and determining whether the referred information coincides with the information written by the means for referring.
According to a second aspect of the present invention there is provided a portable storage device detachable that is detachably connectable information processing unit, the portable storage device including: a first storage unit whose storage contents are held when the portable storage device is disconnected from the information processing unit; a second storage unit whose storage contents are held when the portable storage device is connected to the information processing unit, and the storage contents are not held when the portable storage device is disconnected from the information processing unit; and a control circuit responsive to instructions sent from the information processing unit for controlling reading and writing information from/to the first storage unit and the second storage unit.
According to a third aspect of the present invention, there is provided an information processing unit, to which a portable storage device having a non-volatile storage region and a volatile storage region is detachably connectable, the information processing unit including: means for accessing the non-volatile storage region; means for reading particular information stored in the non-volatile storage region of the portable storage device; means for writing information to the volatile region of the portable storage device when the information processing unit and the portable storage device are connected; and means for referring to the information written to the volatile storage region, for determining whether the referred information coincides with the information by the means for writing and for, instructing the means for reading to re-read the particular information if the referred information and the set information do not coincide.